Solution to level 13 in Untrusted: http://alex.nisnevich.com/untrusted/

untrusted-lvl13-solution.js

/*
 * robotMaze.js
 *
 * The blue key is inside a labyrinth, and extracting
 * it will not be easy.
 *
 * It's a good thing that you're a AI expert, or
 * we would have to leave empty-handed.
 */

function startLevel(map) {
    map.getRandomInt = function(min, max) {
        return Math.floor(Math.random() * (max - min + 1)) + min;
    }

    map.placePlayer(map.getWidth()-1, map.getHeight()-1);
    var player = map.getPlayer();

    map.defineObject('robot', {
        'type': 'dynamic',
        'symbol': 'R',
        'color': 'gray',
        'onCollision': function (player, me) {
            me.giveItemTo(player, 'blueKey');
        },
        'behavior': function (me) {
            var canMove = [
            	me.canMove('right'),
            	me.canMove('up'),
                me.canMove('left'),
                me.canMove('down')
            ];
            me.dir = me.dir || 0;
            var straight = canMove[me.dir],
            	right = canMove[me.dir === 3 ? 0 : me.dir + 1],
                left = canMove[me.dir === 0 ? 3 : me.dir - 1];
            if (right) {
              	setDir(me, 1);
                move(me);
            } else if (straight) {
            	move(me);
            } else if (left) {
            	setDir(me, -1);
                move(me);
            } else {
            	setDir(me, 2);
                move(me);
            }
        }
    });
    var dirs = ['right', 'up', 'left', 'down'];
    function setDir(obj, chg) {
    	var dir = obj.dir + chg;
    	while (dir < 0) {
        	dir += dirs.length;
        }
        while (dir >= dirs.length) {
        	dir -= dirs.length;
        }
        obj.dir = dir;
    }
    function move(obj, dir) {
    	obj.move(dirs[obj.dir]);
    }
    (function(){if(false){
            
        }
    });

    map.defineObject('barrier', {
        'symbol': '░',
        'color': 'purple',
        'impassable': true,
        'passableFor': ['robot']
    });

    map.placeObject(0, map.getHeight() - 1, 'exit');
    map.placeObject(1, 1, 'robot');
    map.placeObject(map.getWidth() - 2, 8, 'blueKey');
    map.placeObject(map.getWidth() - 2, 9, 'barrier');

    var autoGeneratedMaze = new ROT.Map.DividedMaze(map.getWidth(), 10);
    autoGeneratedMaze.create( function (x, y, mapValue) {
        // don't write maze over robot or barrier
        if ((x == 1 && y == 1) || (x == map.getWidth() - 2 && y >= 8)) {
            return 0;
        } else if (mapValue === 1) { //0 is empty space 1 is wall
            map.placeObject(x,y, 'block');
        } else {
            map.placeObject(x,y,'empty');
        }
    });
}

function validateLevel(map) {
    map.validateExactlyXManyObjects(1, 'exit');
    map.validateExactlyXManyObjects(1, 'robot');
    map.validateAtMostXObjects(1, 'blueKey');
}

function onExit(map) {
    if (!map.getPlayer().hasItem('blueKey')) {
        map.writeStatus("We need to get that key!");
        return false;
    } else {
        return true;
    }
}